1. Field of the Invention
This invention relates to a method of producing a power transmission chain and a press-fitting apparatus used in this method, and more particularly to a method of producing a power transmission chain suitably used in a continuously variable transmission (CVT) of a vehicle such as an automobile and a press-fitting apparatus used in this method.
2. Related Art
As a continuously variable transmission for an automobile, there is known the type (chain type continuously variable transmission (as shown in FIG. 5) which comprises a drive pulley 2 having a fixed sheave 2a and a movable sheave 2b and operatively connected to an engine, a driven pulley 3 having a fixed sheave 3b and a movable sheave 3a and operatively connected to a drive wheel, and an endless power transmission chain 1 extending around the two pulleys. Each movable sheave 2b, 3a is moved toward and away from the corresponding fixed sheave 2a, 3b by a hydraulic actuator, and by doing so, the chain 1 is clamped by hydraulic pressure, and by this clamping force, a contact load is caused to develop between each pulley 2, 3 and the chain 1, and a torque is transmitted by a frictional force of this contact portion
One known power transmission chain suited for such a continuously variable transmission comprises a plurality of links having pin passage portions, and a plurality of pins which interconnect the links arranged in a chain width direction, and each pin is fixed to the link by press-fitting. There is proposed in JP-A-2006-95583 a method of producing such a power transmission chain, in which a required number of pins are retained in a pattern corresponding to a final arrangement of the pins of the assembled chain such that the pins are disposed vertically and are arranged at a predetermined pitch. In this condition, the links are press-fitted one by one on the pins such that the links are stacked from lower end portions of the pins.
In the power transmission chain of this kind, the plurality of links arranged in the chain width direction are disposed symmetrically with respect to a centerline disposed centrally of the width of the chain. In the above conventional power transmission chain-producing method, the links are press-fitted on the pins in such a manner that the links are stacked from the lower end portions of the pins, and therefore the position of those links press-fitted at a final stage and disposed at the upper end portions of the pins is often considerably varied by the influence of precision of a plate thickness of the links, etc., so that the projecting amount of the pins from the row of links (arranged in the chain width direction) at one end portions of the pins is different from the projecting amount of the pins at the other end portions thereof. This variation in the projecting amount of the pins causes noises.